Thermostatic heating plug



Allg 5, 1941- R. A. SEGLER 2925L556 THERMOSTATIC HEATING PLUG Filed July 9, 1938 Patented Aug. 5, 1941 UNHTED STATES PATENT @Fiill THERMOSTATIC HEATENG PLUG Richard A. Siegler, Oak Park, Ill.

Application July 9, 1938, Serial No. $18,371

(Cl. 2MB- 46) 2 Claims.

This invention relates to a heating plug and particularly to that type of plug which isv used for heating Huid in a container. In one form it is applied to a hot water bottle to heat the uid in the bottle and to retain it at a constant temperature. It may of course be used for heating a wide va `iety of iiuids in various sorts of containers.

It has for one object to provide a ready means for heating uid, and has for another object to provide means for maintaining that fluid at a denite temperature. It has for a third object to provide means for maintaining the iiuid at any one of a plurality of predetermined temperatures.

Other objects will appear from time to time in the course of the specification and Claims.

The invention is illustrated more or less diagrammatically in the accompanying drawing, wherein:

Figure 1 is a side elevation of one form of my plug with parts in section and parts broken away;

Figure 2 is a longitudinal cross section taken at line 2 2 of Figure 1 on an enlarged scale;

Figure 3 is a transverse section taken at line 3-3 of Figure 2;

Figure 4 is a transverse section taken at line lime of Figure 2;

Figure 5 is a transverse section taken at line 5-5 of Figure 2;

Figure 6 is a longitudinal section showing a modified form;

Figure 7 is a transverse sectional detail taken at line l-l of Figure 6; and

Figure 8 is schematic illustration of the wiring.

Like parts are indicated by like symbols throughout the specification and drawing.

I is a body portion. As shown, it is provided with a hollow or a cavity 2 within which the thermostatic mechanisms are largely situated. Obviously, instead. of this arrangement, the thermostat-S might be mounted above the body and the invention is not limited to the arrange ment in which the body has a cavity. The purpose of the cavity is mainly to economize space and to reduce the overall length or size of the assembly. The body I has a reduced extension 3 which may be threaded as at 4, and may have a still further reduced extension 5. This latter is hollow as at 6 as shown, and provided in its sides with perforations l', and preferably has an open end.

An electrode 9 may take the form of a rod and may be cast or otherwise secured in the body and arranged to extend inwardly into the cavity 2 provided such a cavity is present. Ii not, it extends inwardly to any suitable point in the assembly, where it may be readily joined to a connection member Ill. As here shown, the member II? is reduced at one end and is secured to the electrode 9 by a screw Il. At a point somewhat distant from the screw it is laterally enlarged as at I2. The electrode extends through the body and into the hollow extension 5.

Surrounding the electrode 9 is a second tubular or hollow electrode I3 which is positioned within the body and may be cast in position in it. This electrode It lies partly at least within. the hollow extension 5 and is perforated accordingly as at Id. A connection member I5 lies within the body and extends from the hollow electrode I3 to some point convenient for attachment to a wire or the source of current. A cover I is removably secured upon the housing member I. It be reduced as at Il and perforated as at IS to permit a conduit I9 to pass outwardly.

Mounted upon the member I2 are three thermostatic members 20, 2l, 22, carrying each respectively a Contact point 23, 24 and 25. Positioned upon the housing member I is an insulated support member 2G, which is movably held in place by screws 2l, 2l. Positioned upon the support 2S are contact members 28, 2B and 3l). Each of them is positioned above one of the thermostatie elements. Thus the member 28 is above the thermostat 29, the member 29 above the thermostat 2I and the member above the thermostat 22. Adjusting screws 3|, E2 and 33 are mounted in each of the contact members 2S, 29 and and the adjustment of the contact of the separate thermostats is accomplished by adjustment of the screws 3i, 52 and Ordinarily the thermostats are set at different temperatures so that, depending upon which is in circuit, the temperature at which the heating device will be held may be varied by the adjustment of the circuit. Conductors 3ft, 35 and 36 are connected respectively to the contact members 28, 29 and 33. These pass outwardly through the conduit l to a switch 3l, which has an adjusting wheel or element 33, by means o which the switch is adjusted to bring one or another of the several thermostats into circuit.

The member i5, which is attached to the cylindrical electrode I3, is connected to a wire or conductor 60, which also passes through the conduit I9 and to the switch 31. By this means, the

circuit may be adjusted to bring one or another' of the thermostats into operation. It is important to notice that the same circuit is used throughout, so far as the heating plug is concerned, because whichever of them is in position to control the temperature within the heating plug, the total circuit is in use and the same electrodes are in use. This is in contradistinction to the devices oi the sort in which the heating element comprises several sections and a temperature is maintained by using/one or more sections of the heating element. In this case, the same heating element is used for every position of adjustment, the difference being that the thermostat is set to alter the heating, but the same heating elements are used throughout.

In the modified form shown in Figures 6 and 7, the thermostatic assembly is substantially the same as that shown in the earlier forms. The diiference is that the switch is positioned in the plug and not in the conduit. This has the advantage of simplifying the wiring circuit and reducing the quantity of wire which is necessitated outside the plug. The thermostatic mechanism differs only slightly from that shown in the earlier iigures. Thus if Figures 3 and '7 are compared, it will be seen that instead of the relatively smaller contact elements 28, there are shown somewhat larger contact and switch elements 39, and I connected respectively to the thermostats 2B, 2l and 22. The adjusting screws are the same as before, and the position of the insulated support 25, held in place by the screws Z1, is the same as that above described.

In order to accommodate the switch mechanism, there is used in the forms oi Figures 6 and 7, instead of the relatively light shell or outer closing portion il, a somewhat thicker shell QZ. This is hollow as shown, and provided with a switch comprising a shaft d3, which is engaged in a bearing tube M to which a connector 25 is secured. A wire or conductor i3 is joined to the connector The shaft 43 extends outwardly from the housing 122 and is provided with an operating knob if! and an index member 8, by means of which its position of adjustment may be indicated. Mounted on the inner end of the shaft 33 is a switch member 39, a spring 5U may be positioned about the shaft 3 to bear against the member 5i to which the switch arm 43 may be secured and there elsewhere upon the housing or upon the tube M. Thus, the switch is held against an accidental displacement. As in the case of the earlier forms of the device, the conductor 39 is connected to the outer electrode I3.

The housing is perforated as at 52 and the conduit 53 may pass outwardly through this perforation.

From the schematic diagram of Figure 8, the operation of the device will be evident. As there illustrated, the thermostatic element is diagrammatic, the switch arm is indicated at X and a conductor Y is indicated as connected with the switch arm so that the switch arm may be moved to be connected to either one or another of the thermostats. The thermostats are set each for a dierent temperature and thus the temperature at which the heating device is held depends upon the adjustment oi the switch and upon the particular adjustment of the individual thermostat which is in circuit. The operation is substantially the same whether in the form of Figure 6 or 7 or in the earlier form, because whether or not the switch is located in the housing or in the conduit, its operation is substantially the same and the eieot is to direct the current to one or another of the thermostats.

As shown also in the schematic diagram of Figure 8, an additional conductor SI, and its corresponding additional switch point may be added. The conductor 6l, is connected to the connection member I9, or to its enlargement l2. The pui'- pose of this conductor and its connection is to permit a direct connection so that the electrode may be heated without the control of a thermostat.

Frequently when using the device, it is initially desirable to have it heated up as rapidly as possible and thereafter to maintain it at a controlled temperature. When that is desired the switch is moved to bring the direct conductor into circuit and the device will be heated as rapidly as possible. After it has been heated up to a maximum or to approximately the desired temperatures, the switch setting is changed and it is set to bring into circuit the thermostat which will maintain the temperature at the desired point.

The showing of the direct conductor has been included only in the schematic diagram and it is to be understood that the direct conductor may be omitted or included in each of the devices shown in the several figures.

I claim:

l. In a fluid heating plug, a direct conductor, a plurality of electrodes positioned adjacent each other, said electrodes adapted to be positioned in the iiuid to be heated, whereby current passes from one to the other through said iiuid, and means for adjusting the temperature at which said plug operates, said means comprising a plurality of thermostats positioned sufcientiy close to said electrodes to be heated thereby, electric conductors connected to said electrodes, and selectively to said thermostats, and a switch means for bringing said direct conductor or one or another of said thermostats into circuit whereby the temperature at which the device is maintained is varied in accordance with a predetermined setting of one or another of said thermostats.

2. In a iiuid heating plug, a direct conductor, a plurality of electrodes positioned adjacent each other, said electrodes adapted to be positioned in the fluid to be heated, whereby current passes from one to the other through said iiuid, and means for adjusting and for maintaining constant the temperature at which said plug operates, said means comprising a plurality of thermostats positioned sufficiently close to said electrodes to be heated thereby, electric conductors connected to said electrodes, and selectively to said thermostats, and a switch means for bringing said direct conductor or one or another of said thermostats into circuit whereby the temperature at which the device is maintained is varied in accordance with a predetermined setting of one or another of said thermostats.

RICHARD A. SIEGLER. 

